Chapter 10:
Experimental Methods

By Tom Lawson

From Building Aerodynamics

Overview

Experimentation in aerodynamics started with Wind Tunnels, and still the majority of the experimental work is carried out in them. The new contender is Computer Fluid Dynamics (CFD): this science is developing and has its own advocates: the author is not one of these. Consequently any reader wishing to learn about CFD and its application to Building Aerodynamics will have to consult a book on that subject, he will find no help in these pages.

Building Aerodynamics is a very experimental subject, and has grown out of Aircraft Aerodynamics. The description of the wind is very complex, compared to the still air through which aircraft fly for most of their life. The wind has shear and turbulence which can only be described in statistical terms, and can approach from any direction. The shapes used are bluff shapes which cause the air to separate as it flows around them, rather than smooth sleek shapes, like wings and fuselages, to which the flow is attached.

Even with agreeable conditions, the aircraft aerodynamist had to resort to experimental measurements to quantify the parameters which theory showed were important

The aircraft engineers developed wind tunnel techniques which solved their problems satisfactorily, and, by the middle of the twentieth century, the body of techniques and experience was impressive.

By the middle of the twentieth century buildings, other than cathedral and similar buildings, were beginning to increase in size and reduce in weight so that wind loads began to form an important part of the...

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